Development of statistically based methods to determine QC/QA testing levels for hot-mix asphalt construction

Constructing a quality Hot Mix Asphaltic Concrete (HMA) Overlay is a common objective shared by state highway agencies (agencies) and contractors. This dissertation provides a rational method to determine the minimum level of testing necessary to satisfactorily construct HMA overlays for both state highway agency (agencies) and contractor. Testing levels were defined as the frequency of sampling and testing necessary to provide satisfactory quality control and acceptance.; A work plan was designed to isolate individual testing components commonly found in Quality Control/Quality Assurance (QC/QA) specifications and determine their significance using collected construction data from 16 HMA overlay projects in six states. Nine testable hypotheses were specifically developed to evaluate test properties, variation, specification limits, distribution of samples within a lot, and pay factors. Testing data were then analyzed using developed testable hypotheses in the context of quality control, acceptance, and verification testing levels.; Analysis of quality control test data found that significant between-day variation exists for plant-mixing and compaction processes. A rational method for determining the number of daily density tests was provided using a standard statistical equation. A process for determining acceptance testing levels was developed using the hypothesis test conclusions. A consistent finding was that the number of samples within a lot affects the ability to achieve specification limits and the pay factor.; A statistical procedure was developed to determine the number of verification tests between the agency and contractor using split-sample test results. A developed equation calculates testing tolerances for using historical field data and statistical input parameters. A bias-correction procedure was developed for the verification process that evaluates the differences between labs at start of the project.; Recommendations and findings were synthesized to provide guidelines and a case application of how the research results can be applied to actual specifications and to a particular project. Practical issues to consider when implementing the research results into practice were also provided. Finally, recommendations for future research were given.